Radiation-induced Reactions of (2-Methyl-5-nitro-1H-imidazole-1-ethanol)nickel(II) in Aqueous Solution: A Flash-photolysis and Steady-state Gamma-radiolysis Study

DOI: 10.1039/DT9930002485

Source and publish data:

Journal of the Chemical Society, Dalton Transactions p. 2485 - 2490 (1993)

Update date:2022-08-28

Topics:

Authors:

Roy, Maitrayee Basu

Mandal, Parikshit C.

Bhattacharyya, Sudhindra N.

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Article abstract of DOI:10.1039/DT9930002485

On gamma radiolysis of the nickel(II) complex of metronidazole (2-methyl-5-nitro-1H-imidazole-1-ethanol), hydroxyl radicals and the hydrated electron e(1-) (aq) react with the complex leading to the destruction of the nitroimidazole structure.The loss of the complex and the production of nitrite have been followed by steady-state experiments, while the transient kinetics of the hydroxyl reactions have been probed by flash photolysis.The OH radicals react with the complex with a rate constant of ca. 4.0E9 dm³ mol^-1 s^-1, resulting in elimination of the nitro groupeither by adding to the C⁵ position or through generation of a nickel(III) species.The latter undergoes intramolecular electron transfer from the ring with a rate constant of ca. (4.6 +/- 0.4)E3 s^-1, while the imidazole radicals formed decay by second-order kinetics with a 2k/ε value of (9.1 +/- 1.3)E5 cm s^-1.The hydrated electrons generate the nitroanion radicals, a fraction of which undergoes denitration while the rest is reduced by a successive four-electron scheme to a hydroxylamino derivative.